BACILLUS-COLI-LlKE BACTERIA FROM FECES AND SEWAGE 35 



The Voges-Proskauer-positive strains (aerogenes-cloacae group) 

 form somewhat less acid from glucose, but more acid from maltose, 

 sucrose, glycerol, and dulcitol, and possibly also from raffinose and 

 salicin, than do the Voges-Proskauer-negative strains (colon-bacillus 



Acid-formation should not be given precedence over gas-formation 

 in studies on B. coli, for the acid may be masked by a secondary alkali- 

 production. In general, however, acid-production is accompanied by 

 gas-formation. With sucrose, dulcitol, and raffinose, acid-production 

 and gas-formation are almost perfectly correlated. The correlation is 

 less marked in the case of salicin, while the line of demarcation 

 between gas-formers and nongas-formers, as indicated by quantitative 

 acid-production from glycerol, is very indistinct. 



Practically all Voges-Proskauer-positive and bovine strains attack 

 salicin with liberation of gas. This glucosid is fermented less fre- 

 quently by the organisms from pig, horse, sheep, man, and sewage 



Gas is formed from sucrose as follows: Voges-Proskauer-positive 

 ( Voges-Proskauer-negative strains ) . 



strains 100%, sheep 95.6%, horse 79%, cow 50%, pig 32.3%, sewage 

 (Voges-Proskauer-negative strains) 26%, and human strains 12%. 



Of 2601 human strains of B. coli studied by different investigators, 

 in various countries and at different times, only 35.3% have been 

 sucrose-fermenters. 



Motility, as determined in semisolid nutrient agar, seems to be an 

 important character. Only 32% of the human and 20% of the Voges- 

 Proskauer-negative sewage strains are motile, as compared with 

 93.7% of pig, 80% of cow, 77.3% of sheep, and 100% of horse strains. 



